Terminal and method for audio data transmission

ABSTRACT

Aspects of the disclosure provide a terminal adapted to transmit audio data via Bluetooth to a device. The terminal includes a controller adapted to detect configuration parameters of the device and optimally determine configuration parameters of the terminal, and a transmission module capable of transmitting a packet of a first packet type based on a first mode of the terminal and a packet of a second packet type based on a second mode of the terminal. The audio data is modulated by a first modulation mode in the first mode and the audio data is modulated by a second modulation mode in the second mode that is more efficient than the first modulation mode. When the device cannot operate in the second mode but can operate in the first mode, the controller causes the transmission module to create a packet of the first packet type containing the audio data.

CROSS REFERENCE TO RELATED APPLICATION

The present continuation application claims the benefit of priorityunder 35 U.S.C. 120 to application Ser. No. 14/724,509 filed on May 28,2015, the entire contents of which is hereby incorporated herein byreference.

BACKGROUND

The background description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent the work is described in thisbackground section, as well as aspects of the description that may nototherwise qualify as prior art at the time of filing, are neitherexpressly nor impliedly admitted as prior art against the presentdisclosure.

Bluetooth™ is a wireless technology that is widely used as a short rangedata communications platform for connecting many devices for manyapplications including audio streaming. Bluetooth enhanced data rate(EDR) is an enhanced Bluetooth technology that offers high speed datarate for the Bluetooth communication.

SUMMARY

Aspects of the disclosure provide a terminal adapted to transmit audiodata via Bluetooth to a device. The terminal includes a controlleradapted to detect configuration parameters of the device and optimallydetermine configuration parameters of the terminal, and a transmissionmodule capable of transmitting a packet of a first packet type based ona first mode of the terminal and a packet of a second packet type basedon a second mode of the terminal. At the transmission module, the audiodata is modulated by a first modulation mode in the first mode and theaudio data is modulated by a second modulation mode in the second modethat is more efficient than the first modulation mode. When the devicecannot operate in the second mode but can operate in the first mode, thecontroller causes the transmission module to create a packet of thefirst packet type containing the audio data.

In an example, the terminal further includes a sub band coding (SBC)encoder adapted to encode the audio data using SBC with a bitpool value,and, when the device cannot operate in the second mode but can operatein the first mode, the controller is adapted to configure the bitpoolvalue to be equal or smaller than a bitpool threshold.

In an embodiment, when the device can operate in both the first mode andthe second mode, and has a logical link control and adaptation protocol(L2CAP) maximum transmission unit (MTU) size equal to or smaller than aMTU size threshold, the controller causes the transmission module tocreate a packet of the first packet type containing the audio data.

In an example, the terminal further includes a sub band coding (SBC)encoder adapted to encode the audio data using SBC with a bitpool value,and, when the device can operate in both the first mode and the secondmode, and has a L2CAP MTU size equal to or smaller than a MTU sizethreshold, the controller is adapted to configure the bitpool value tobe equal or smaller than a first bitpool threshold.

In an embodiment, the first packet type is 2DH5 packet and the secondpacket type is 3DH5 packet. In another embodiment, the first bitpoolthreshold is a maximum bit pool value in a range of bitpool value wherea frequency band occupancy rate maintains a same level.

In an embodiment, when the device can operate in both the first mode andthe second mode, and has a L2CAP MTU larger than a MTU size threshold,the controller causes the transmission module to create a packet of thesecond packet type containing the audio data.

In an example, the terminal further includes a sub band coding (SBC)encoder adapted to encode the audio data using SBC with a bitpool value,and, when the device can operate in both the first mode and the secondmode, and has a L2CAP MTU larger than a MTU size threshold, thecontroller is adapted to configure the bitpool value to be equal orsmaller than a second bitpool threshold.

In an embodiment, the controller is adapted to configure a plurality ofbitpool thresholds corresponding to a plurality of sound quality levelsfor a SBC encoder.

Aspects of the disclosure provide a method for transmitting audio datavia Bluetooth from a terminal to a device. The method includes detectingconfiguration parameters of the device, preparing a packet of a firstpacket type or a packet of a second packet type based on the detectedconfiguration parameters of the device, and transmitting the packet ofthe first type containing the audio data to the device when the devicecannot receive the packet of the second type but can receive the packetof the first type.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of this disclosure that are proposed as exampleswill be described in detail with reference to the following figures,wherein like numerals reference like elements, and wherein:

FIG. 1 shows exemplary configurations of a terminal for transmittingaudio data using Bluetooth™ according to an embodiment of thedisclosure;

FIG. 2 shows the structure of a terminal according to an embodiment ofthe disclosure;

FIG. 3 shows the structure of a device according to an embodiment of thedisclosure;

FIG. 4 shows an exemplary protocol message exchange process between aterminal and a device according to an embodiment of the disclosure;

FIG. 5 shows a flowchart of an exemplary configuration process of asource for transmitting audio data to a sink via Bluetooth EDR accordingto an embodiment of the disclosure;

FIGS. 6A-6D show some exemplary baseband packets according to anembodiment of the disclosure;

FIGS. 7A and 7B show relationship between the frequency band occupancyrate and the sub band coding (SBC) bitpool value according to anembodiment of the disclosure; and

FIG. 8 shows a table including exemplary configurations of a terminalaccording to different user options for sound quality according to anembodiment of the disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 shows exemplary configurations of a terminal 10 for transmittingaudio data using Bluetooth™ according to an embodiment of thedisclosure. As shown, the terminal 10 communicates with a device 20A,20B or 20C using Bluetooth to transmit audio data. Although threedevices 20A, 20B and 20C are shown in FIG. 1, only one of the threedevices 20A-20C can operate with the terminal 10 at a time in anembodiment. Of cause, in alternative embodiments, the terminal 10 cancommunicate with multiple devices simultaneously.

The terminal 10 can be a smart phone (such as an android phone, aniPhone phone, a windows phone, and the like), a computer (such asdesktop, laptop, tablet, and the like), or any other device that iscapable of transmitting audio data using Bluetooth. The device 20A, 20Bor 20C can be a headset, a speaker, a television, a computer, or anydevice that is capable of receiving audio data using Bluetooth. Inaddition, in Bluetooth communication, a device of a transmission side,such as the terminal 10, is called a source and a device of thereceiving side, such as the device 20A-20C is called a sink.

In an embodiment, the terminal 10 can transmit data using Bluetooth EDR.When transmitting data using Bluetooth EDR, the terminal 10 can operatein different EDR modes. Particularly, the terminal 10 can operate in afirst mode, referred to as EDR2M mode (fixed), or a second mode,referred to as EDR3M mode. EDR2M mode (fixed) means a fixed bit ratemode using a bit rate of 2 Mbps, and EDR3M mode means a variable bitrate mode that can change between the EDR3M mode having a maximum bitrate of 3 Mbps and a mode, referred to as variable EDR2M mode, having amaximum bit rate of 2 Mbps. When operating in the first mode, theterminal can obtain a maximum data rate of 2 Mbps by using a firstmodulation, referred to as pi/4 differential quaternary phase shiftkeying (pi/4 DQPSK) modulation. When operating in the second mode, theterminal can obtain a maximum data rate of 3 Mbps by using a secondmodulation, referred to as eight phase differential phase shift keying(8DPSK) modulation that is more spectrally efficient than the firstmodulation in terms of obtaining faster data rate for fixed bandwidth.In addition, the terminal 10 uses a baseband (BB) packet to transmitaudio data. Particularly, the terminal 10 uses a first-mode based BBpacket for transmitting the audio data when operating in the first mode,and uses a second-mode based BB packet for transmitting the audio datawhen operating in the second mode. The first-mode based BB packet canhave three different packet types, such as 2DH1 packet, 2DH3 packet, and2DH5 packet, and the second-mode based BB packet can also have threedifferent packet types, such as 3DH1 packet, 3DH3 packet, and 3DH5packet. Each packet can have a payload field among other fields, and therespective size of the payload field of different packet types can bedifferent. For example, in an embodiment, the payload size of a 3DH5packet is 1021 bytes, and the payload size of a 2DH5 packet is 679bytes.

In an embodiment, the terminal 10 can adapt its operation mode accordingto a corresponding operation mode configuration of the device 20A-20C.For example, during an initial communication setup process between theterminal 10 and the device 20A, the terminal 10 can detect the modeconfiguration of the device 20A-20C, and accordingly determine asuitable operate mode for itself. In an example, the device 20A can onlyoperate on the EDR2M mode (fixed), and accordingly the terminal 10 canconfigure itself to operate in the EDR2M mode (fixed) and communicatewith the device 20A in the EDR2M mode (fixed). In another example, thedevice 20B is capable of operating in the EDR2M mode (fixed) as well asthe EDR3M mode, and the terminal 10 can choose to operate in the EDR2Mmode (fixed) or the EDR3M mode based on other configuration parametersof the device 20B, or environmental conditions, such as interferencesfrom surrounding equipment.

In an embodiment, the terminal 10 can use a sub band coding (SBC)encoder to compress audio data and subsequently generate SBC frames. Thesize of a SBC frame can be determined by a parameter called “bitpoolvalue”. When the bitpool value increases, the compression degreedecreases and the size of the SBC frame increases, and accordingly thesound quality of the transmitted audio data increases. In addition, theSBC frames can be transmitted to a logical link control and adaptationprotocol (L2CAP) packet generator that can package the SBC packets intoa L2CAP packet. Generally, a maximum transmission unit (MTU) sizeparameter is defined for a L2CAP packet at both a source and a sink, andan application using the L2CAP packet generator for data transmissioncan limit the size of the data packet transmitted to the L2CAP packetgenerator below the MTU size limit.

Further, the L2CAP packets can be transmitted to a BB packet generatorwhere the L2CAP packets are segmented into BB packets having certainpayload sizes for transmission over the air. When segmenting a L2CAPpacket into multiple BB packets, a blank space may be arranged when bitsof segmentations of the L2CAP packets cannot fully fill a BB packet. Theexistence of blank space can reduce the efficiency of the wireless datatransmission leading to a waste of wireless frequency occupation.

Generally, Bluetooth devices operate on the 2.4 GHz frequency band whichis shared by many other applications, such as cordless phones, nearfield communication (NFC) devices, and wireless computer networks. Thus,when the terminal 10 perform Bluetooth data transmission, a lowoccupancy rate of the 2.4 GHz frequency band is preferable in order toreduce interference to other applications. In addition, a loweroccupancy rate of the 2.4 GHz frequency band can decrease theprobability of the interference received from other applications whilethe terminal 10 performs Bluetooth audio data transmission.

According to an aspect of the disclosure, when performing audio datatransmission using the Bluetooth EDR, the terminal 10 can optimallyconfigure the bitpool value, and the BB packet type to increase soundquality and decrease the frequency band occupancy rate.

As shown in FIG. 1, three exemplary configurations of the terminal 10are illustrated. In the first example, the terminal 10 transmits audiodata to the device 20A that is capable to operate only in EDR2M mode(fixed). The terminal 10 is configured to operate in EDR2M mode (fixed)and use packets of 2DH5 packet type for the data transmission. Inaddition, the bitpool value is configured to be equal to or smaller thana bitpool value 59. Note that, the suitable value of bitpool value isnot limited to 59, and any other suitable value may be adopted, forexample, 57 or 66. In the second example, the terminal 10 transmitsaudio data to the device 20B that is capable to operate in both EDR2Mmode (fixed) and EDR3M mode. Because the MTU size defined for the L2CAPpackets of the device 20B is set to be 1000 or smaller than 1000, theterminal 10 is configured to operate in EDR2M mode (fixed) and usepackets of 2DH5 packets for the data transmission. In addition, thebitpool value is configured to be equal to or smaller than a bitpoolvalue 59. Note that, the suitable value of bitpool value is not limitedto 59, and any other suitable value may be adopted, for example, 57 or66. In the third example, the terminal 10 transmits audio data to thedevice 20C that is capable to operate in both EDR2M mode (fixed) andEDR3M mode, however, the MTU size defined for the L2CAP packets of thedevice 20C is set to be greater than a MTU size 1000. Accordingly, theterminal 10 is configured to operate in EDR3M mode and use packets of3DH5 packet type for the data transmission. In addition, the bitpoolvalue is configured to be equal to or smaller than a bitpool value 64.Note that, the suitable value of bitpool value is not limited to 64, andany other suitable value may be adopted, for example, 65 or 77.

FIG. 2 shows the structure of the terminal 10 according to an embodimentof the disclosure. The terminal 10 can include an audio data inputmodule 11, a SBC encoder 12, a packet generator 13, a transmissionmodule 14, an antenna 15 and a controller 16. Those elements 11-16 arecoupled together as shown in FIG. 2.

The audio data input module 11 can be configured to obtain audio datafrom outside of the terminal 10. For example, the input module 11 canuse a microphone to receive an audio signal and subsequently performencoding with an encoder, such as a pulse code modulation (PCM) encoder,to generate digitalized audio data. Alternatively, the audio data inputmodule 11 can obtain the audio data stored in the memory (not shown) ofthe terminal 10. The audio data is then transmitted to the SBC encoder12.

The SBC encoder 12 can be configured to compress the audio data togenerate SBC frames based on the bitpool value configuration of theterminal 10, and transmit the SBC frames to the packet generator 13. SBCis used for encoding and decoding audio data for Bluetooth audio datatransmission from a source to a sink, such as a headphone orloudspeaker, and is specified by the Bluetooth Special Interest Group(SIG).

The packet generator 13 can include a L2CAP packet generator that can beconfigured to receive the SBC frames from the SBC encoder 12 and packagethe SBC frames into a L2CAP packet. The Bluetooth logical link controland adaptation protocol is used within the Bluetooth protocol stack, andcan support higher-level protocol multiplexing, packet segmentation andreassembly. The L2CAP can generate L2CAP packets with a payloadconfigurable up to 64 kB, with 672 bytes as the default MTU size, and 48bytes as the minimum mandatory supported MTU size.

The packet generator 13 can include a baseband (BB) packet generatorthat can be configured to segment the L2CAP packets into BB packets. Asdescribed earlier, BB packets can be of different types depending on theEDR2M mode (fixed) or the EDR3M mode the terminal 10 operates in. Forexample, when the terminal 10 operates in EDR2M mode (fixed), 2DH5packets can be used for audio data transmission; when the terminal 10operates in EDR3M mode, 3DH5 packets can be used. The generated BBpackets are transmitted to the transmission module 14.

The transmission module 14 can be configured to receive the BB packetsand transmit the BB packets over the air via the antenna 15 usingsuitable modulations, such as pi/4 DQPSK modulation or 8DPSK modulation.

The controller 16 includes circuitry configured to control andcoordinate the audio data processing operations at the elements 11-14.For example, the controller can be configured to detect theconfiguration parameters of the device 20A-20C by exchanging messageswith the device 20A-20C using certain protocols. In addition, thecontroller 16 can optimally determine the configuration parameters ofthe terminal 10, such as the bitpool values, the EDR modes, and BBpacket types, in order to acquire higher sound quality and lowerfrequency band occupancy rate.

In various embodiments, the audio data input module 11, the SBC encoder12, the packet generator 13, the transmission module 14 and thecontroller 16 can be implemented using any suitable software orhardware. For example, the controller 16 can be implemented as softwarestored in a storage module (not shown) and executed by a centralprocessing unit (CPU) not shown. In another example, the transmissionmodule 14 can be implemented using application specific integratedcircuit (ASIC).

FIG. 3 shows the structure of the device 20A-20C according to anembodiment of the disclosure. The devices 20A, 20B and 20C have the samestructure but different audio data processing capabilities and parameterconfigurations. As shown, the device 20A-20C can includes an antenna 21,a reception module 22, a packet reassembler 23, a SBC decoder 24, anaudio data output module 25, and a controller 26.

The reception module 22 can be configured to receive radio signals viathe antenna 21, generate the BB packets and transmit the BB packets tothe packet reassembler 23. In some examples, the reception module 22 canoperate in EDR2M mode (fixed) or EDR3M mode. In other examples, thereception module 22 can only operate in EDR2M mode (fixed). The packetreassembler 23 can include a L2CAP packet reassembler that can beconfigured to collect data in multiple BB packets and reassemble thedata into a L2CAP packet. In addition, the packet reassembler 23 caninclude a SBC frame generator that can be configured to generate SBCframes from a L2CAP packet. The generated SBC frames are transmitted tothe SBC decoder 24.

The SBC decoder 24 can be configured to decode the compressed audio datacontained in the SBC frames to produce audio data in an uncompressedformat. The produced audio data are transmitted to the audio data outputmodule 25. The Audio data output module 25 can be configured to outputan audio signal from a speaker, such as a speaker in a headset.

The controller 26 can be configured to control and coordinate theoperations at the elements 22-25.

FIG. 4 shows an exemplary protocol message exchange process between theterminal 10 and the device 20A-20C according to an embodiment of thedisclosure. Generally, during the Bluetooth communication, a source candetect the configuration parameters of the sink through suitableprotocols. The configuration parameters can include EDR modecapabilities, range of supported bitpool values, L2CAP MTU size, and thelike. The suitable protocols can include service discovery protocol(SDP), audio/video distribution transport protocol (AVDTP), and thelike.

In FIG. 4, a first phase of the protocol message exchange process canuse the SDP protocol and include steps S1 and S2.

At S1, the terminal 10 can transmit a [CAPABILITY] message to the device20A-20C to inquire the EDR mode capability information.

At S2, the device 20A-20C can transmit a [RESPONSE] message as aresponse to the reception of the [CAPABILITY] message to notify theterminal 10 of the EDR mode compatibility of the device 20A-20C. Forexample, as shown in FIG. 4, a message of [EDR2M (fixed) support, EDR3Mno] is notified to the terminal 10 indicating that the device 20A canonly support EDR2M mode (fixed). In the case of the device 20B or 20C, amessage of [EDR2M (fixed) support, EDR3M support] is notified to theterminal 10 indicating that the device 20B or 20C can support both EDR2Mmode (fixed) and EDR3M mode.

Further in FIG. 4, a second phase of the protocol message exchangeprocess can use the AVDTP protocol and include steps S3 and S4.

At S3, the terminal 10 can transmit a [CAPABILITY] message to the device20A-20C to enquire the range of supported bitpool values.

At S4, the device 20A-20C can transmit a [RESPONSE] message as aresponse to the reception of the [CAPABILITY] message to notify theterminal 10 of a range of the supported bitpool value. For example, asshown in FIG. 4, a message of [bitpool Max/Min] is notified to theterminal 10 indicating that the device 20A-20C can support a bitpoolvalue from a minimum value to a maximum value.

Similarly, the terminal 10 can obtain a MTU size configuration parameterof the device 20A-20B using a suitable protocol, such as the L2CAPprotocol.

FIG. 5 shows a flowchart of an exemplary configuration process 500 of asource for transmitting audio data to a sink via Bluetooth EDR accordingto an embodiment of the disclosure. During the Bluetooth EDRcommunication, the source can optimally configure the bitpool value andthe BB packet type to increase sound quality and decrease the frequencyband occupancy rate. The terminal 10 and the device 20A-20C are used todescribe the process 500. In addition, the configuration parameters usedin the configuration process 500, such as EDR mode capabilities, rangeof supported bitpool values, L2CAP MTU size, and the like, can beobtained during the protocol message exchange process described in theFIG. 4 example.

The process 500 starts at S10 and proceeds to S11.

At S11, the controller 16 in the terminal 10 determines the EDR modesupported by the device 20A-20C. If the device, such as the device 20A,can only operate in EDR2M mode (fixed), the process 500 proceeds to S13.If the device, such as the device 20B or 20C can support both EDR2M modefixed) and EDR3M mode, the process proceeds to S12.

At S12, the controller 16 determines the L2CAP MTU size supported by thedevice 20A-20C. If the MTU size supported by the device 20A-20C islarger than a MTU size threshold value, such as 1000, the process 500proceeds to S13. Otherwise, the process 500 proceeds to S14. Note that,the MTU size threshold value is not limited to 1000, and any othersuitable value may be adopted, for example, 950 or 1050.

At S13, under the control of the controller 16, the SBC encoder 12 inthe terminal 10 can choose a bitpool value that is equal or smaller thana first bitpool threshold value, such as 59, for the SBC encodingoperation. For example, if the device 20A-20C does not support the bitpool value 59 but supports the bit pool value between 49 to 57 accordingto the [CAPABILITY] message sent at S4 of FIG. 4, the terminal 10 canchoose a bitpool value 57 which is maximum value between 49 to 57 andmost close to the bit pool value 59. In addition, the transmissionmodule 14 can be configured to operate in EDR2M mode (fixed) and use the2DH5 packet for the audio data transmission.

At S14, under the control of the controller 16, the SBC encoder 12 canchoose a bitpool value that is equal or smaller than a second bitpoolthreshold value, such as 64, for the SBC encoding operation. Forexample, if the device 20A-20C does not support the bit pool value 64but supports the bit pool value between 57 to 62 according to the[CAPABILITY] message sent at S4 of FIG. 4, the terminal 10 can choose abitpool value 62 which is maximum value between 57 to 62 and most closeto the bit pool value 64. In addition, the transmission module 14 can beconfigured to operate in the EDR3M mode and use the 3DH5 packet for theaudio data transmission.

FIGS. 6A-6D show some exemplary BB packets according to an embodiment ofthe disclosure.

FIG. 6A shows a 2DH5 packet transmitted in EDR2M mode (fixed). The 2DH5packet includes an AVDTP header and five SBC frames as its payload. TheSBC frames are carried by a L2CAP packet and an MTU size defined for theL2CAP packet equals to 672 bytes. Each SBC frame has a length of 119bytes corresponding to a bitpool value of 53. As shown, a blank space of65 bytes occurs at the end of the 2DH5 packet.

Similarly, FIG. 6B shows a 2DH5 packet that includes an AVDTP header andfive SBC frames as its payload, and the SBC frames are carried by aL2CAP packet and an MTU size defined for the L2CAP packet equals to 672bytes. However, each SBC frame has a length of 131 bytes correspondingto a bitpool value of 59. Consequently, a blank space of 6 bytes occursat the end of the 2DH5 packet. Thus, in FIG. 6B, the configuration ofbitpool value changes from a smaller value, 53, to a larger value, 59,leading to higher sound quality than in the FIG. 6A example, however,the amount of the 2DH5 packets needed for the transmission do notchange, maintaining the same frequency band occupancy rate as in FIG.6A.

Further in the FIG. 6B example, if the bitpool value continues toincrease to a value above 59, the size of the SBC frame will increaseaccordingly. As a result, the amount of SBC frames contained in the 2DH5will decrease, for example, to 4 or less frames due to the size limit ofthe 2DH5 packet. Thus, a blank space will occur at the end of the 2DH5,exhibiting a situation similar to the FIG. 6A example where the bitpoolvalue can be continually increased from the current value whilemaintaining the same frequency band occupancy rate. In addition, as onemore 2DH5 packet is needed to transmit the same amount of uncompressedaudio data previously transmitted using only one 2DH5 packet, the amountof the 2DH5 packets needed for the transmission increases, leading to anincreased frequency occupancy rate from that corresponding to thebitpool value 59.

Based on the above description, a certain bitpool value, such as thebitpool value 59, can be used as a bitpool threshold. When the bitpoolvalue is configured to be equal or less than the bitpool threshold, thefrequency band occupancy rates corresponding to the different bitpoolvalues can be maintained at the same level. On the other side, when thebitpool value is configured to be greater than the bitpool threshold,the frequency band occupancy rate can increase to another level.

FIG. 6C shows a 3DH5 packet transmitted in EDR3M mode. The 3DH5 packetincludes a plurality of SBC frames and an AVDTP header as its payload.The SBC frames are carried by a L2CAP packet and an MTU size defined forthe L2CAP equals to 1017 bytes. Each SBC frame has a length of 131 bytescorresponding to a bitpool value of 59. As shown, a blank space of 88bytes occurs at the end of the 3DH5 packet.

FIG. 6D shows a 2DH5 packet and a 2DH3 packet transmitted in variableEDR2M mode. The 2DH5 packet and 2DH3 packet each includes a plurality ofSBC frames and an AVDTP header as its payload. The SBC frames arecarried by a L2CAP packet and an MTU size defined for the L2CAP packetequals to 1017 bytes. Each SBC frame has a length of 131 bytescorresponding to a bitpool value of 59.

In FIG. 6D, compared with the FIG. 6C example, the same amount of frames(7 frames) contained in one 3DH5 packet in FIG. 6C are packaged into one2DH3 packet and one 2DH3 packet due to the limit capacity of the 2DH5packet and the 2DH3 packet. Particularly, the 2DH5 packet has a capacityof 672 bytes and contains five SBC frames at its payload, while the 2DH3packet has a capacity of 367 bytes and contains two SBC frames at itspayload, plus a blank space. As specified in the Bluetooth standard, the3DH5 packet, 2DH5 packet and 2DH3 packet occupy 5, 5, and 3 time slots,respectively, when transmitted over the air. Thus, for the transmissionof the same amount of audio data carried in the SBC frames, using 3DH5packets can consume less time slots. Therefore, 3DH5 packets transmittedin EDR3M mode is preferable to other packet types transmitted invariable EDR2M mode in order to decrease the frequency band occupancyrate.

FIGS. 7A and 7B show relationship between the frequency band occupancyrate and the SBC bitpool value according to an embodiment of thedisclosure. As shown, vertical axes represent the frequency bandoccupancy rate and horizontal axes represent the SBC bitpool valueparameter.

FIG. 7A shows three broken lines d11, d12, and d13 corresponding to afirst L2CAP MTU size, for example, equal to 895, while FIG. 7B showsthree broken lines d21, d22 and d23 corresponding to a second L2CAP MTUsize, for example, equal to 1017. The broken lines d11 and d21 canrepresent a situation where the terminal 10 operates in the EDR3M modeusing the 3DH5 packet for audio data transmission. The broken lines d12and d22 can represent a situation where the terminal 10 is fixed byconfiguration at an initial communication setup stage to operate in theEDR2M mode (fixed) using the 2DH5 packet for audio data transmission. Oncontrast, the broken lines d13 and d23 can represent a situation wherethe terminal 10 previously operated in the EDR3M mode using the 3DH5packet but currently operates in the variable EDR2M mode using packettypes, such as 2DH5 and 2DH3, for audio data transmission. The change ofthe modes can be caused by interferences from surrounding equipment or“preferred_rate” command issued by a user of the terminal 10.

As shown in FIGS. 7A and 7B, each of the broken lines can includemultiple segments corresponding to different rages of SBC bitpool value.For example, in FIG. 7A, the broken line d11 can include multiplesegments S111-S117. The segment S111 corresponds to a range of SBCbitpool value from 43 to 48, the segment S112 corresponds to a range ofSBC bitpool value from 48 to 49, and so on. For another example, thebroken line d12 can include multiple segments S121-S126. The segmentS121 corresponds to a range of SBC bitpool value from 40 to 41, and thesegment S122 corresponds to a range of SBC bitpool value from 41 to 48,and so on.

In addition, at certain segments, such as S115 and S124, the frequencyband occupancy rates maintain at the same level. For example, on thebroken line d11, the SBC bitpool values 48, 56, and 66 are the bitpoolthresholds as described in the FIGS. 6A and 6B examples. Consequently,in the ranges of the SBC bitpool value where the SBC bitpool values aresmaller than or equal to the thresholds, the frequency band occupancyrates maintain at the same level. For example, in the range of SBCbitpool value from 57 to 66 corresponding to the segment S115, thefrequency band occupancy maintains a level of about 22% that does notchange when the SBC bitpool values change from 57 to 66. Therefore, atthese certain segments, sound quality can be increased withoutincreasing the frequency band occupancy rate by configuring a larger SBCbitpool value.

Furthermore, for different L2CAP MTU size configurations of a source,such as the MTU sizes of 895 and 1017 in FIGS. 7A and 7B, respectively,the level of frequency band occupancy rate of the variable EDR2M modeare different. Particularly, the frequency band occupancy raterepresented by the broken line d13 corresponding to the MTU size 895 ishigher than that represented by the broken line d23 corresponding to theMTU size 1017. However, the level of the frequency band occupancy rateof the EDR2M mode (fixed), represented by the broken lines d12 and d22,does not change according the different MTU size. Consequently, for asmaller MTU size value, such as the MTU size of 895, the frequency bandoccupancy rate of the variable EDR2M mode is worse than that of theEDR2M mode (fixed), while for a larger MTU size value, such as the MTUsize of 1017, the frequency band occupancy rate of the variable EDR2Mmode is similar to that of the EDR2M mode (fixed).

Based on the above description, a source, such as the terminal 10, canbe configured to operate in the EDR2M mode (fixed) to avoid the worsefrequency band occupancy rate when the MTU size is below a MTU sizethreshold, such as a MTU size of 1000, even the device 20B-20C iscapable to operate in EDR3M mode. For example, in an embodiment, in aninitial communication setup process, the terminal 10 may detect that thedevice 20B-20C is capable to operate in EDR3M mode and the device 20Bhas a MTU size smaller than the threshold, such as a MTU size of 895 inthe FIG. 7A example, and subsequently choose to operate in EDR3M modecorresponding to the broken line d11. However, the device 20B-20C canlater detect that a packet loss rate is above a predetermined thresholddue to interference from other communication equipment, and send acommand to the terminal 10 to decrease the data rate. As a response, theterminal 10 may change the operate mode from EDR3M mode to the variableEDR2M mode corresponding to the broken line d13. Thus, the terminal 10can be operating in a situation with the worse frequency band occupancyrate corresponding to the broken line d13 in FIG. 7A. To avoid thesituation, the terminal 10 can choose to operate in the EDR2M mode(fixed) during the initial communication setup stage after detecting theMTU size that is smaller than the MTU size threshold. This fixed operatemode corresponds to the broken line d12 in FIG. 7A.

On the other side, when the MTU size is above the MTU size threshold,such as the MTU size of 1000, the source, such as the terminal 10, canbe configured to operate in the EDR3M mode using 3DH5 packets for theaudio data transmission to take advantage of the high data rate of theEDR3M mode. For example, the terminal 10 can detect that the device 20Cis capable to operate in EDR3M mode and have a MTU size larger than theMTU size threshold, the terminal 10 can choose to operate in EDR3M modewith 3DH5 packet size corresponding the broken line d21 in FIG. 7B. Incase that the interference from other equipment causes the terminal 10to change mode to the variable EDR2M mode, corresponding to the brokenline d23, the level of the frequency occupancy rate will essentially bethe same level of the EDR2M mode (fixed) corresponding to the brokenline d22.

FIG. 8 shows a table including exemplary configurations of the terminal10 according to different user options for sound quality according to anembodiment of the disclosure. As shown, in an embodiment, whenperforming audio data transmission using Bluetooth EDR technology, auser of the terminal 10 can choose from three levels of sound quality:high quality, medium quality and low quality. Corresponding to differentconfigurations of a sink device, such as the device 20A-20C, for eachsound quality level, the terminal 10 as the source device can beconfigured with different configurations shown in FIG. 8.

In a first example, as shown in the second column of the table, a sinkdevice, such as the device 20A, is only capable to operate in EDR2M mode(fixed). Accordingly, the terminal 10 can be configured to operate inEDR2M mode (fixed) and use 2DH5 packets for the audio data transmission.This configuration corresponds to the broken lines d12 or d22 in FIGS.7A and 7B. In addition, for the three sound quality levels, the terminal10 can choose three different bitpool thresholds, respectively.Particularly, a bitpool threshold of 75 can be configured for the highsound quality level, a bitpool threshold of 59 for the medium soundquality level and a bitpool threshold of 48 for the low sound qualitylevel.

In a second example, as shown in the third column of the table, a sinkdevice, such as the device 20B, is capable to operate in both EDR3M andEDR2M mode (fixed), and is configured with a MTU size equal to orsmaller than a MTU size threshold, such as a MTU size of 1000.Accordingly, the terminal 10 can choose the same configurations of EDRmode, BB packet type, and bitpool threshold, as in the second column,for each option of the sound quality levels. Thus, the terminal 10operates in the EDR2M mode (fixed).

In a third example, as shown in the fourth column of the table, a sinkdevice, such as the device 20C, is capable to operate in both EDR3M andEDR2M mode (fixed), however, is configured with a MTU size greater thana MTU size threshold, such as a MTU size of 1000. Accordingly, theterminal 10 can be configured to operate in EDR3M mode and use 3DH5packets for the audio data transmission. In case the surroundinginterference causes the packet loss rate to be above a threshold, theterminal 10 can change from EDR3M mode to variable EDR2M mode withvariable packet types. This configuration corresponds to the brokenlines d21 and d23 in FIG. 7B. In addition, for the three sound qualitylevels, the terminal 10 can choose three different bitpool thresholds,respectively. Particularly, a bitpool threshold of 64 can be configuredfor the high sound quality level, a bitpool threshold of 55 for themedium sound quality level and a bitpool threshold of 48 for the lowsound quality level.

While aspects of the present disclosure have been described inconjunction with the specific embodiments thereof that are proposed asexamples, alternatives, modifications, and variations to the examplesmay be made. Accordingly, embodiments as set forth herein are intendedto be illustrative and not limiting. There are changes that may be madewithout departing from the scope of the claims set forth below.

1. (canceled)
 2. A terminal adapted to transmit data to a device via adata communications platform, comprising: circuitry configured to detectconfiguration parameters of the device; and prepare one of a firstpacket of a first packet type based on a first mode of the terminal anda second packet of a second packet type based on a second mode of theterminal, wherein, when the device cannot support the second mode butcan support the first mode, the circuitry is configured to transmit thefirst packet of the first packet type containing the data to the device,when the device supports both the first mode and the second mode, andhas a protocol size equal to or smaller than a threshold, the circuitryis configured to transmit to the device the first packet of the firstpacket type containing the data, and when the device supports both thefirst mode and the second mode, and has the protocol size larger thanthe threshold, the circuitry is configured to transmit to the device thesecond packet of the second packet type containing the data.
 3. Theterminal of claim 2, wherein the data communications platform is ashort-range data communications platform.
 4. The terminal of claim 3,wherein the short-range data communications platform is a datacommunications platform for connecting a plurality of devices for aplurality of applications.
 5. The terminal of claim 2, wherein the datais modulated by a first modulation scheme in the first mode and the datais modulated by a second modulation scheme in the second mode.
 6. Theterminal of claim 5, wherein the second modulation scheme is morespectrally efficient than the first modulation scheme.
 7. The terminalof claim 2, wherein the terminal is configured to communication with aplurality of devices via the data communications platformsimultaneously.
 8. The terminal of claim 2, wherein the terminal isconfigured to communication with a plurality of devices via the datacommunications platform, one at a time.
 9. A method for transmittingdata from a terminal to a device via a data communications platform,comprising: detecting, using circuitry of the terminal, configurationparameters of the device; preparing, using the circuitry of theterminal, one of a first packet of a first packet type based on a firstmode of the terminal and a second packet of a second packet type basedon a second mode of the terminal; when the device cannot support thesecond mode but can support the first mode, transmitting, using thecircuitry of the terminal, the first packet of the first packet typecontaining the data to the device; when the device supports both thefirst mode and the second mode, and has a protocol size equal to orsmaller than a threshold, transmitting, using the circuitry of theterminal, to the device the first packet of the first packet typecontaining the data; and when the device supports both the first modeand the second mode, and has the protocol size larger than thethreshold, transmitting, using the circuitry of the terminal, to thedevice the second packet of the second packet type containing the data.